My issues with Strongswan in the OpenWRT trunk are now resolved. Strongswan 4.5.1-1 is available.
I recently purchased a Buffalo WZR-HP-G300NH router and installed OpenWRT on it. I used the trunk version, but found that StrongSwan4 did not allow me to pass traffic, despite an identical configuration to my working Trendnet router. I can successfully connect, but my log files show an error “unable to add SAD entry.” My client indicated no proposal. Though I have not discovered the full nature of the issue, I did notice that the current OpenWRT trunk does not include the kmod-mod-imq module. Since the networking component has changed, I wondered if that might be related. When I installed the 10.03.1-rc4 version of OpenWRT instead, things worked again.